Stem Cell Therapy for Spinal Cord Injuries Reaches Clinical Trials

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Researchers are unlocking the potential of stem cells to develop new ways of treating Parkinson’s disease, cancer and even injuries to the spinal cord.

Tom Okarma, CEO, president and director of Geron, a publicly traded technology company based in California, is starting the first phase of clinical trials for a human embryonic stem cell-based therapy to treat subacute thoracic spinal cord injuries. The first site for the trial is Northwestern Medicine.

At the World Stem Cell Summit in Detroit, Okarma sat down with Medill News Service and Science in Society to talk about the goals and methods of the study.

Tom Okarma (photo provided by Ben Richmond/MEDILL)Tom Okarma (photo provided by Ben Richmond/MEDILL)What are the goals of a Phase I trial?
It’s a Phase I safety trial, so the primary outcome measures are safety, but the way you document safety is the same way you document a response. So ultimately what we hope to achieve in the most severely injured cases – what we call complete injuries – is not to restore function, but rather to shift their outcome from one of no hope or responsiveness to any intervention to an outcome more like an incomplete injury – patients who have a less severe injury and who can respond over time to physical therapy. If we could try that, it would be an out-of-the-park home run.

Were you involved in choosing Northwestern as a site for the program?
As CEO I have a say in where we go for these programs. The centers that we are bringing up and getting online are all “neural trauma referral centers” in the United States, meaning that patients [with a severe spinal cord injury] can be referred – medevaced if you will – to them from as far away as a thousand miles. We spent a lot of time selecting the centers and training multiple elements in each center to be able to participate in this trial.

How do you find patients?
For technical reasons we’re limited to patients who had their injuries within two weeks of the time of [treatment]. That’s based on animal work that shows that after three or four months after the injury there’s so much scarring in the spinal cord that we literally can’t get the cells in there. So this is a therapy that is unfortunately limited to new cases of spinal cord injury. We’ve have had many, many requests from patients not only with chronic injuries but from patients with all sorts of injuries. And unfortunately we have to tell them no.

Where do the stem cells come from?
The stem cells are derived from embryos (from in vitro fertilization) that are no longer needed to achieve pregnancy and…are grade B, if you will. Every embryo that is created for IVF is examined under the microscope, and only the [embryos that look normal] are implanted. So there is a judgment made by the IVF physician on which embryos are likely to achieve normal pregnancy. The ones that are left over are the ones that can be, under informed consent, donated by the couple who no longer need them for research of all kinds. And one of those is the derivation of a human embryonic stem cell line from such a grade B embryo.

Once the line is derived, however, it is immortal. So we create master and working cell banks that are [made up of] many, many vials of these purified cells that can be expanded indefinitely for technical reasons. The master cell bank to make the spinal cord injury product has 250 vials, and it contains enough expansion capacity for us to dose all of the spinal cord patients in North America for the next 20 years. That’s how expandable the technology is.

Do you have a time frame for either this safety trial at Northwestern or for the completion of the therapy?
It all depends on what we find. The design of a registration trial (the next phase) is based off the safety trial that you create. So until we have that data under our belt it’s just hand waving.

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